1. Field of the Invention
This invention generally relates to improving video and graphics quality.
2. Description of Related Art
Televisions, computer monitors and other display devices exist in a great multitude of display sizes and aspect ratios. For example, conventional television displays have a 4:3 (1.33:1) aspect ratio (hereafter referred to as a standard display) while widescreen displays, such as theater or HDTV displays, have a 16:9 (1.78:1) aspect ratio. There are also still wider displays having aspect ratios of 2.39:1 or 2.35:1. Moreover, a given display unit should be able to display the great multitude of video signal formats that exist. In order for a given display unit to display a format other than its own native format, various techniques are used to shrink or extend the aspect ratio of the normative format. Many of these techniques involve projecting the normative image in its original format onto the native display and simply blackening the “gaps” where no image information exists.
Letterboxing is the practice of transferring wider video formats, such as 16:9, to more square formats while preserving the original aspect ratio. The resulting video display must include masked-off areas above and below the picture area, often referred to as black bars, or, more accurately, as mattes. In contrast, pillar boxing, or window boxing, is necessitated when video that was not originally designed for widescreen is shown on a widescreen display. The original material is shrunk and placed in the middle of the widescreen frame while vertical black bars are placed on either side. Furthermore there are sometimes instances in which standard ratio images are presented in the central portion of a letterboxed picture, resulting in a black border all around. This effect is referred to as match boxing, and obviously wastes a great deal of screen space as well as reduces the resolution of the original image.
Therefore, in some instances a substantial amount of display real estate may actually not be displaying any video at all being used to merely accommodate a black border, for example. Therefore, the presence of these blank areas not only reduces the size and/or resolution of the original image, any video enhancement or other processing would in effect be rendered useless in the blank areas resulting in inefficient use of computing and/or memory resources.
In addition to accommodating a displayed image having a format that is not native to the display screen, other situations where a video image is surrounded by a non-video background or is embedded in a non-video frame (such as a picture in picture where the secondary video is embedded in frame having a skin (such as a Windows-type border) that often includes control buttons, or information icons.
Therefore, it would be desirable to automatically determine the location of edges of a video window.